package com.icehand.common.utils;

import com.alibaba.fastjson.JSONObject;

import java.security.MessageDigest;
import java.util.Arrays;
import java.util.Set;

/**
 * @author icehand
 */
public class MD5Utils {
	private final static String[] hexDigits = {"0", "1", "2", "3", "4", "5", "6", "7",
			"8", "9", "a", "b", "c", "d", "e", "f"};

	/**
	 * 转换字节数组为16进制字串
	 * @param b 字节数组
	 * @return 16进制字串
	 */
	public static String byteArrayToHexString(byte[] b) {
		StringBuilder resultSb = new StringBuilder();
		for (byte aB : b) {
			resultSb.append(byteToHexString(aB));
		}
		return resultSb.toString();
	}

	/**
	 * 转换byte到16进制
	 * @param b 要转换的byte
	 * @return 16进制格式
	 */
	private static String byteToHexString(byte b) {
		int n = b;
		if (n < 0) {
			n = 256 + n;
		}
		int d1 = n / 16;
		int d2 = n % 16;
		return hexDigits[d1] + hexDigits[d2];
	}

	/**
	 * MD5编码
	 * @param origin 原始字符串
	 * @return 经过MD5加密之后的结果
	 */
	public static String MD5Encode(String origin) {
		String resultString = null;
		try {
			resultString = origin;
			MessageDigest md = MessageDigest.getInstance("MD5");
			resultString = byteArrayToHexString(md.digest(resultString.getBytes("UTF-8")));
		} catch (Exception e) {
			e.printStackTrace();
		}
		return resultString;
	}

	public static String createSign(JSONObject params){
		if(null == params || params.isEmpty()){
			return "";
		}

		Set<String> keySet = params.keySet();
		Object[] keys = keySet.toArray();
		Arrays.sort(keys);
		StringBuilder sb = new StringBuilder();
		boolean isFirst = true;
		for(Object key : keys) {
			if(!isFirst){
				sb.append("&");
			}
			sb.append(key);
			sb.append("=");
			sb.append(params.get(String.valueOf(key)));
			isFirst = false;
		}

		return sb.toString();
	}
}